Linear amplification device with a non-linear amplification element for a mobile radio device

ABSTRACT

A system and method to optimize the efficiency of an amplifier device is provided by the including a non-linear amplifier in a mobile radio device. A phase displaced signal in relation to the input signal is respectively produced in the amplifier device with a non-linear power amplifier and in a plurality of push-pull successive phase modifiers, and the outputs of the phase modifier are connected by a passive component.

FIELD OF TECHNOLOGY

The present disclosure relates to a method and a device for optimizingthe efficiency of an amplifier arrangement with a non-linear poweramplifier, preferably in a mobile radio device.

BACKGROUND

As part of the further development of mobile radio from the GSM standardto EDGE or further on to the UMTS standard, new demands are being madeon the transmission characteristics of power amplifiers. Previously,information was transmitted as pure phase information (GMSK), however,recent developments require that the amplitude be also evaluated forinformation transmission. This results in more stringent requirementsfor the transmission characteristics of power amplifiers. On the onehand the amplifier element must be linear, and on the other hand thetransmission characteristics must not depend on temperature changes andoperating voltage variations. However, this is not always the case usingtransistors. Often times linear and non-linear distortions need to beminimized. To achieve this, a pre-equalization in the base band orintermediate frequency or in the form of a closed loop such as a polarloop is implemented. However, in each case a significant balancingand/or circuit overhead is required with such an arrangement.

Accordingly, an efficient and cost-effective amplifier arrangement isneeded.

BRIEF SUMMARY

The present disclosure illustrates an amplifier arrangement having anon-linear power amplifier (LV) and two successive push-pull phasemodifiers (PS), where a signal offset in phase to the input signal isgenerated in each case. Afterwards, the phase modifiers powerdissipation is converted at a passive component. The passive componentis connected to the outputs of the phase modifiers. A passive componentcan, for example, be a load balancing resistor or a symmetricaltransformer with a subsequent rectifier arrangement. After the poweramplifier, the amplitude-modulated signal is divided up into two signalparts of equal size or part powers and routed via two push-pull phasemodifiers. The use of a symmetrical transformer as the component isparticularly advantageous. The voltage uncoupled in the symmetricaltransformer in this case is forwarded to a rectifier and the directcurrent output by the rectifier is routed to a supply unit as chargecurrent. One advantage of this amplifier arrangement is that theefficiency of this arrangement can be decisively improved. Furthermore,the present method and arrangement of very cost effective.

BRIEF DESCRIPTION OF THE DRAWINGS

The various objects, advantages and novel features of the presentdisclosure will be more readily apprehended from the following DetailedDescription when read in conjunction with the enclosed drawings, inwhich:

FIG. 1 illustrates a power amplifier with subsequent modulation feed andload balancing resistor, and

FIG. 2 illustrates an amplifier arrangement for feeding back electricalenergy to a supply unit of a mobile radio device.

DETAILED DESCRIPTION

FIG. 1 shows an amplifier arrangement for implementing a linearamplifier system with non-linear amplifier components. Two phasemodifiers PS controllable with a modulation signal are connected after aC-class power amplifier LV (where efficiency can be realized in practicein the range of 75%). The circuit of FIG. 1 can be implemented with anyclass of amplifier (A, B or CC). However, the efficiency may be degradedwith an amplifier LV operated other than in C class mode.

After the power amplifier LV, the generated signal or the power PRF isdivided up into two part signals or part powers of equal size PRF 1 andPRF 2. These part powers are routed via the push-pull phase modifiersPS. In accordance with amplitude information, the power (RF) isconverted as power dissipation in the load balancing resistor LAW.Amplitude information in this case is envelope curve information. Themain disadvantage of this circuit arrangement also arises here.Corresponding to the crest factor (ratio of peak power to average power)the C-class power amplifier LV must be arranged for the peak power to betransmitted. However in such a circuit arrangement this leads to a largepart of the RF power generated PRF being converted in the load balancingresistor LAW.

FIG. 2 shows a amplifier arrangement for feeding back electrical energyto a supply unit of a mobile radio device. The power amplifier LV fromFIG. 1 can again be seen in this diagram operating in C-class mode withsubsequent power separation PRF 1 and PRF 2 and the controllable phasemodifiers PS. The circuit of FIG. 2 works with any class of amplifier(A, B or C), however the efficiency may be degraded with a poweramplifier LV operated other than in C mode. Omitted from this diagram isthe load balancing resistor LAW which is replaced by a symmetricaltransformer SÜ (ballun). Furthermore, a rectifier arrangement GRconnected to a direct current supply unit VE is added. The task of thisnew circuit arrangement is to route the dissipated power (HF) of thepower supply unit (battery, ac adapter etc.) previously converted in theload balancing resistor LAW to a mobile radio device, and a mobilestation for a cellular mobile radio network, as direct current. Afterthe power amplifier LV, power components PRF 1 and PRF 2 are routed viathe phase modifiers PS. The electrical length or the throughput time ofthe power components PRF 1 and PRF 2 is influenced with phase modifiersPS. Thus, as an example, power component PRF 1 is increased in path 1 byphase modifier PS, and the delay time in path 2 is reduced by the otherphase modifier PS (push-pull). This is achieved through two vectorswhich have the same phase angle before the phase modifier PS and aredifferent after the phase modifier PS. This produces a different lengthof sum vector for the addition of the two subvectors before and afterthe phase modifiers PS as regards the amount. The phase modifiers PS arecontrolled by an amplitude modulation signal, which, for example, can bean audio signal, video signal or similar information. The amplitudemodulation signal can be decoupled from the input signal (usefulsignal). However it can also be any given signal. If the control voltageof the phase modifiers PS is not equal to zero, there is a voltage dropat the symmetrical transformer SÜ. The control voltage corresponds tothe amplitude modulation signal and is thus zero when the modulationvoltage is zero, via the symmetrical amplifier SU this voltage istransmitted on the secondary side of the transformer SÜ and referencedthere to a potential. In this example, this is represented by a groundsymbol. A reference to a battery potential, for example, is however alsoalways conceivable. Subsequently, the voltage is rectified with amultipath rectifier and filtering is performed. The greatest efficiencyis preferably obtained with a multipath rectifier. It would also bepossible to use another rectifier. The direct current set can then befed to the supply unit VE. To optimize the functionality of the overallcircuit the input impedance of the rectifier GR should be almostindependent of amplitude. If the input impedance of the rectifier is notconstant, non-linear distortions are created which affect the functionof the overall circuit. To transmit all signal components free ofdistortion, the C amplifier LV is designed for transmitting the maximumpeak power occurring in the circuit. This means that the amplifier LVruns with a constant power which lies above the average power requiredat the output by the crest factor. With normal transmission procedures,the crest factor lies in the range 3 dB to 10 dB. If the amplifier LV isdimensioned for a crest factor of 10 dB, this means that for thearrangement with a load balancing resistor LAW (FIG. 1), appr. 90% ofthe generated power would be a converted in the load balancing resistorLAW as power dissipation. With the expanded circuit there is now theopportunity of capturing a this power dissipation component (HF) andfeeding it to a supply unit VE as charge current. An HF (powerdissipation)-DC (direct current) conversion is thus performed.

The above described description and drawings are only to be consideredillustrative of exemplary embodiments, which achieve the features andadvantages of the invention. Modifications and substitutions to specificprocess conditions and structures can be made without departing from thespirit and scope of the invention. Accordingly, the invention is not tobe considered as being limited by the foregoing description anddrawings, but is only limited by the scope of the appended claims.

1-20. (canceled)
 21. An apparatus for optimizing the efficiency of anamplifier arrangement comprising: a non-linear power amplifier in amobile radio device; and a plurality of push-pull phase modifierscoupled to said amplifier, wherein said phase modifiers generate asignal offset in phase form an input signal and wherein the outputs ofthe phase modifiers are coupled to a passive component.
 22. Theapparatus according to claim 21, wherein a symmetrical transformerincluded in the amplifier arrangement is used as the passive component.23. The apparatus according to claim 21 wherein power is obtained at thepassive component after the phase modifiers.
 24. The apparatus accordingto claim 21, wherein an amplitude modulated signal is generated by theamplifier arrangement by means of fed amplitude information.
 25. Theapparatus according to claim 21, wherein a load balancing resistor isused in the amplifier arrangement as the passive component.
 26. Theapparatus according to claim 22, wherein a voltage is decoupled in thesymmetrical transformer that is rectified in a rectifier, and whereinthe direct current output by the rectifier is fed to a supply unit ascharge current.
 27. The apparatus according to claim 25, wherein poweris dissipated in load balancing resistor.
 28. The apparatus according toclaim 21, wherein the push-pull phase modifiers are controlled using amodulation signal.
 29. The apparatus according to claim 27, wherein thepower dissipation is referenced in a symmetrical amplifier to a voltagepotential.
 30. The apparatus according to claim 21, wherein a signalgenerated by the power amplifier is divided into two part signals ofequal size and fed to the plurality phase modifiers.
 31. The apparatusaccording to claim 26, wherein the input impedance of the rectifier isamplitude-independent.
 32. The apparatus according to claim 26, whereina single-path or multipath rectifier is used as the rectifier.
 33. Theapparatus according to claim 21, wherein the maximum peak power arisingin the power amplifier can be transmitted with a deviation of up to 6dB.
 34. The apparatus according to claim 21, wherein the transmittedpower of the power amplifier is up to 6 dB around the crest factor abovethe average power required at the output.
 35. The apparatus according toclaim 31, further comprising a supply unit coupled to the poweramplifier, wherein the supply unit is one of a battery and an acadapter.